Sri Lankan Journal of Physics Latest Articleshttps://sljp.sljol.info/articles/Latest articles published by Sri Lankan Journal of Physicsen-usFri, 15 Jan 2021 21:18:20 -0000Mechanical property evaluation of natural rubber/ vein graphite compositeshttps://sljp.sljol.info/article/10.4038/sljp.v22i1.8082Vein graphite filled natural rubber composites were prepared by keeping the total weight of composites constant in each using suitable dispersant, accelerators, and coagulants to use in high-end applications. All the composites were characterized by using X-ray diffraction (XRD), scanning electron microscopy (SEM), and Fourier transform infrared spectroscopy (FTIR). The tensile properties, Young’s modulus and hardness of the composites were evaluated. XRD and FTIR analysis verified the presence of rubber and graphite in the composites without any noticeable structural changes. The SEM image of composites showed a uniform homogeneous surface of the composites. High tensile strength was observed at 10% of graphite incorporation in natural rubber. Young’s moduli and hardness of composites were observed to be improved with the addition of the dispersed graphite. The hardness of the composites increases with increasing graphite in the composite and optimized at 60% of graphite. The properties of natural rubber/graphite investigated in the present study is useful for many applications including electronic devices, aerospace, automobiles, toys, heavy equipment industry, battery, consumer products, etc. Published on 2021-01-09 12:41:12https://sljp.sljol.info/article/10.4038/sljp.v22i1.8082Exfoliated graphite as electrochemical double layer capacitor electrode: Electrochemical impedance studyhttps://sljp.sljol.info/article/10.4038/sljp.v22i1.8077Exfoliated graphite (EG) is one of the best alternatives for graphene in the electrochemical devices since graphene needed a cost-effective mass production to reach the commercialization. Liquid phase exfoliation has been identified as an inexpensive, ecofriendly method for high quality EG production. Sri Lankan natural graphite and commercially available graphite were used for exfoliation and the converted EG samples were used to fabricate electrochemical double layer capacitors (EDLCs). They were characterized using Electrochemical Impedance Spectroscopy (EIS). <span style="text-decoration: line-through;">EG</span> prepared by Sri Lankan natural graphite showed higher specific capacitance values compared with commercial graphite EG. Thereby, the value of Sri Lankan graphite over commercial graphite was emphasized. Published on 2021-01-09 12:41:04https://sljp.sljol.info/article/10.4038/sljp.v22i1.8077Solutions of Klein-Gordon equation for the modified central complex potential in the symmetries of noncommutative quantum mechanicshttps://sljp.sljol.info/article/10.4038/sljp.v22i1.8079We explore the new analytical solutions for both bound and the new masses of mesons of the Klein–Gordon equation with the modified central complex potential, which describes the heavy light <em>Ǭq</em>, (<em>Q </em>= <em>c</em>, <em>q </em>= <em>u</em>/<em>d</em>, <em>s</em>) mesons and the quarkonium system <em>ǭǭ</em>, (q=c, b, s) via the standard Bopp’s shift method and standard perturbation theory.We have obtained the energy eigenvalues of the ground state <em>E<sup>(0)</sup><sub>nc</sub>(a, b,</em> 0, <em>j, l, m)</em> the first excited state <em>E<sup>(1)</sup><sub>nc</sub>(a, b</em>, 1, <em>j, l, m</em>) and <em>p<sup>th</sup> </em>the excited state <em>E<sup>(p)</sup><sub>nc</sub>(a, b, p, j, l, m)</em> in terms of the shift energy (Δ<em>E</em><sub>cc</sub>(0<em>, j, l, s, m</em>), Δ<em>E</em><sub>cc</sub>(1,<em>j,l,s,m</em>) and Δ<em>E</em><sub>cc</sub>(<em>p, j, l, s, m</em>) and <em>(E</em><sub>0<em>l</em></sub><em>, E</em><sub>1<em>l</em></sub><em> and E<sub>nl</sub>)) </em>of ordinary relativistic quantum mechanics. In addition to the parabolic cylinder functions, the Gamma function, the discreet atomic quantum numbers (<em>j, l, s, m</em>)<em> </em>the potential parameters (<em>a </em>and <em>b</em>) and the noncommutativity parameters (θ and σ). In the second part of the research, we will apply the obtained results to calculate the new masses of the mentioned previously mesons in the symmetries of the relativistic three-dimensional noncommutative quantum mechanics. Moreover, some important special cases in the context of the symmetries of the relativistic three-dimensional noncommutative quantum mechanics are treated. Published on 2021-01-09 12:41:00https://sljp.sljol.info/article/10.4038/sljp.v22i1.8079A theoretical investigation of nonrelativistic bound state solution at finite temperature using the sum of modified Cornell plus inverse quadratic potentialhttps://sljp.sljol.info/article/10.4038/sljp.v21i1.8069New modified nonrelativistic bound state energy eigenvalues have been obtained for the hydrogenic atoms with spin ½ under the sum of modified Cornell plus inverse quadratic potential (MCIQP), at finite temperature, in the symmetries of the noncommutative three-dimensional real space phase (NC: 3D-RSP). The ordinary sum of Cornell plus inverse quadratic potential is extended by including new central terms to become MCIQP. In addition, MCIQP is suggested as a quark–antiquark interaction potential for studying the masses of heavy and heavy–light mesons in (NC: 3D-RSP), in which the potential satisfies the features of quantum chromodynamics theory of strong interaction. For this purpose, the modified radial Schrödinger equation is analytically solved using the generalized Bopp’s shift method and standard perturbation theory. The energy eigenvalues and the corresponding new Hamiltonian operator are obtained in (NC: 3D-RSP). These results are applied to calculate the mass of mesons such as charmonium, bottomoniumand mesons with spin (0 or 1). In a thermal medium of a positive temperature, the new parameters of the studied potential MCIQP become temperature dependent because of color screening. It is found that the perturbative solutions of the discrete spectrum can be expressed on the Gamma function, the discreet atomic quantum numbers and the potential parameters (), in addition to noncommutativity parameters (and). The influence of the induced magnetic field and the coupling parameter of the spin field on some quantum properties of the system have also been studied. The total complete degeneracy of modified energy levels under MCIQP is found to be equal to , which gives a very good indicator that our new treatments produce clear energy values when compared with similar energy levels obtained in ordinary relativistic quantum mechanics (RQM). New mass spectra for the quarkonium systems is found to be equal to the sum of ordinary values in RQM plus two perturbative terms proportional to the parameters (or) and (or) of noncommutativity space-phase. These results are in good agreement with the already existing results in nonrelativistic noncommutative quantum mechanics (NRNCQM) where the physical treatment was done using other potentials such as new modified potential containing Cornell, Gaussian and inverse square terms and modified quark-antiquark interaction potential. Published on 2020-05-29 00:00:00https://sljp.sljol.info/article/10.4038/sljp.v21i1.8069Appraisal of mechanical properties of different particle sizes of palm kernel shell, coconut shell and mixed palm kernel-coconut shells particles epoxy-filled compositeshttps://sljp.sljol.info/article/10.4038/sljp.v21i1.8071<p>This study presents the appraisal of indentation hardness and flexural modulus of composites prepared by mixing particles of palm kernel shell (PKS), coconut shell (CNS) and mixtures of palm kernel-coconut shell (MPKCNS) of different sizes (35.5 μm, 75 μm and 106 μm) with epoxy and hardener for various applications. The Rockwell hardness tester results showed that PKS particles epoxy filled composites of 35.5 μm had the highest hardness number of 77 while the MPKCNS particles epoxy filled composites of 106 μm had the least hardness number of 43. The CNS particles epoxy filled composites of 35.5 μm and 75 μm had relatively higher flex moduli of 428.66 MPa and 425.55 MPa respectively. The particle size of 106 μm had relatively higher flexure extension than 35.5 μm and 75 μm. The Scanning Electron Microscope (SEM) analysis revealed proper adhesion of the shell particles and epoxy resins with little or no pores in the composites. The PKS particles epoxy filled composites of 35.5 μm can be employed to enhance the mechanical properties of the composites for engineering applications.</p> Published on 2020-02-07 00:00:00https://sljp.sljol.info/article/10.4038/sljp.v21i1.8071Influence of Non -thermal Electron Parameter on Heavier Masses of Negative Ion Plasmahttps://sljp.sljol.info/article/10.4038/sljp.v20i0.8062In presence of non-thermal electrons, theoretical investigations on ion-acoustic solitary waves are made in a collisionless unmagnetized warm plasma consisting of positive and negative ions by the well known pseudopotential technique. The influence of non-thermal electron parameter on heavier masses (Q) of negative ion plasma for Sagdeev potential function, first and second order solitary wave solutions are mainly analysed and discussed here properly. Published on 2019-03-28 00:00:00https://sljp.sljol.info/article/10.4038/sljp.v20i0.8062Applicability of natural rubber based polymer electrolyte for electrochemical double layer capacitorshttps://sljp.sljol.info/article/10.4038/sljp.v20i0.8067Natural rubber has received a great interest to be used for electrochemical applications recently. But, Sri Lankan natural rubber has not yet been considered for such activity other than exporting and using for some manufacturing processes. Main objective of the present study is investigating the candidacy of Sri Lankan natural rubber in electrochemical double layer capacitors. Methyl grafted natural rubber was dissolved in tetrahydrofuran and it was later mixed with a Li salt. Using the solvent casting method, it was possible to prepare a thin, bubble free film. It was sandwiched in between two identical Sri Lankan natural graphite electrodes. Performance evaluation was accomplished with cyclic voltammetry, electrochemical impedance spectroscopy and galvanostatic charge discharge test. Single electrode specific capacitance was depending on the potential window and the scan rate of cycling. Nyquist plots confirmed the capacitive behavior at low frequency region. The average specific discharge capacity was 0.31 Fg<sup>-1</sup>. Obtained results show that natural rubber electrolytes are suitable candidates for electrochemical double layer capacitors and they are also encouraging to proceed towards improving the performance further. Published on 2019-03-28 00:00:00https://sljp.sljol.info/article/10.4038/sljp.v20i0.8067Approximate l-States Solutions to the Schrodinger Equation with Manning-Rosen plus Hellmann Potential via WKB Approximation Schemehttps://sljp.sljol.info/article/10.4038/sljp.v19i1.8050The approximate analytical solutions of the radial Schrodinger equation have been obtained by the interaction of Manning-Rosen and Hellmann potentials which is a newly proposed potential. Using the Wentzel-Kramers-Brillouin WKB approach, we obtained the eigenstates solutions for any arbitrary angular momentum. Special cases of potential consideration have been discussed. Eigenenergy solutions to equations obtained play an important role in quantum mechanics because they contain a wealth of vital information regarding the system under consideration. Published on 2018-08-08 00:00:00https://sljp.sljol.info/article/10.4038/sljp.v19i1.8050Dirac Equation with Unequal Scalar and Vector Potentials under Spin and Pseudospin Symmetryhttps://sljp.sljol.info/article/10.4038/sljp.v19i1.8043An approximate solution of the Dirac equation in the <em>D</em>-dimensional space is obtained under spin and pseudospin symmetry limits for the scalar and vector inversely quadratic Yukawa potential within the framework of parametric Nikiforov-Uvarov method using a suitable approximation scheme to the spin-orbit centrifugal term. The two components spinor of the wave function and their energy equations are fully obtained. Some numerical results are obtained for the energy level with various dimensions (<em>D</em>), quantum number (<em>n</em>), vector potential and scalar potential. The results obtained under spin symmetry using either or are equal to the results obtained using. But under the pseudospin symmetry, the results obtained using or are not equal to the results obtained using. Published on 2018-05-15 00:00:00https://sljp.sljol.info/article/10.4038/sljp.v19i1.8043Approximate Analytical Solutions of the Effective Mass Klein-Gordon Equation for Two Interacting Potentialshttps://sljp.sljol.info/article/10.4038/sljp.v19i1.8042In this study, the approximate analytical solutions of the relativistic Klein-Gordon equation in the spatial dimensions with unequal Coulomb-inverse Trigonometry scarf scalar and vector potentials for an effective mass function is investigated in the framework of supersymmetric and shape invariance method by employing a suitable approximation scheme to the centrifugal term. The energy equation for some special cases such as the Coulomb potential and inverse Trigonometry scarf potential are obtained. Using a certain transformation, the non-relativistic energy equation is obtained which is identical to the energy equation of the Hellmann potential. Published on 2018-02-15 00:00:00https://sljp.sljol.info/article/10.4038/sljp.v19i1.8042